Nonalcoholic Fatty Liver Disease
- Nonalcoholic Fatty Liver Disease (NAFLD) is a morphological pattern of liver damage that is very similar to that seen in alcoholic liver disease but is not associated with alcohol abuse. The pathogenesis of NAFLD appears to be related to wholesale derangements in metabolism associated with obesity. In a subset of NAFLD patients, hepatic pathology evolves into one of inflammation with potentially extensive fibrosis, termed Nonalcoholic Steatohepatitis (NASH).
- NAFLD appears as a macrovesicular steatosis that strongly resembles alcoholic hepatic steatosis associated with alcoholic liver disease. When observed grossly, the liver appears fatty.
- NASH is morphologically similar to Alcoholic Hepatitis associated with alcoholic liver disease. Briefly, this is characterized by presence of Mallory bodies in hepatocytes, a predominantly neutrophilic infiltrate, and signs of fibrosis within the Space of Disse and around terminal hepatic venules. A subset of individuals with NASH fibrosis can progress insidiously to a pattern consistent with cirrhosis.
- The pathogenesis of NAFLD and NASH is not well-understood but is highly correlated with the presence of obesity. In some sense, NAFLD and NASH are likely the hepatic manifestation of metabolic syndrome.
- Symptomology associated with NAFLD and NASH is usually mild and often asymptomatic. Some mild fatigue or right upper quadrant discomfort may be present but usually the only manifestation is a mild increase in serum aminotransferases. Long-term presence of NASH and its associated fibrosis may ultimately result in irreversible cirrhosis and its clinical complications.